Abstract: Objective:To investigate the expression and clinical significance of ATP-binding cassette subfamily C member 5 (ABCC5)in lung squamous cell carcinoma(LUSC).Methods:The relevant data sets from the Can-cer Genome Atlas (TCGA), Gene Expression Omnibus (GEO) and ArrayExpress databases were integrated and analyzed to explore the expression of ABCC5 mRNA in LUSC and non-LUSC tissues, and the summary receiver operating characteristic (sROC) curve was drawn.Real-time fluorescence quantitative polymerase chain reaction(RT-qPCR)was used to detect the expression of ABCC5 mRNA in LUSC cell lines(NCI-H1703, NCI-H520)and human normal lung epithelial cells (BEAS-2B).Immunohistochemical (IHC) staining was used to detect the ex-pression of ABCC5 protein in 61 cases of LUSC tissues and 49 cases of corresponding adjacent tissues.The clini-copathological information of LUSC patients was collected and followed up to analyze the relationship between ABCC5 expression and clinicopathological features and prognosis of patients with lung squamous cell carcino-ma.Results:Based on public databases, meta-analysis results suggested that the expression level of ABCC5 mRNA was significantly up-regulated in LUSC tissues(SMD=1.56, 95%CI:1.23-1.89, I²=78.6%, P< 0.001), and the area under the sROC curve (AUC) was 0.95 (95% CI: 0.93-0.97).Compared with BEAS-2B cells, ABCC5 mRNA expression was up-regulated in NCI-H1703 and NCI-H520 cells (P< 0.05).IHC results showed that the expression of ABCC5 protein in LUSC tissues was higher than that in adjacent tissues (P< 0.05), and the differ-ences in the expression of ABCC5 protein in T stage, lymph node metastasis and clinical stage were statistically significant (P< 0.05).Survival analysis showed that there was no significant differ-ence in overall survival rate and progression-free survival rate between the high ABCC5 expression group and the low ABCC5 expression group in LUSC patients (P> 0.05).Conclusion:ABCC5 is highly expressed in LUSC, which may be related to the formation and progression of LUSC.